Diffuser



P. KOLLSMAN DIFFUSER 2 Sheets-Sheet 2 Filed Aug. 27. 1945 o Il Illini.

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rroeA/En Patented Dec. 6, 1949 UNITED STATES ATE Fries Claims. l

This invention relates to dlffusers for rotary compressors or pumps in which the rotational energy of a delivered fluid is converted intol pressure energy.

One object of the invention is the provision of an annular diffuser having a smaller radial length for a given change in cross-sectional area throughout its radial length.

Another object of the invention is an annular diffuser having a smaller radial length for a given conversion of rotary energy to pressure energy.

Another object of the invention is a diffuser according to the preceding objects in which the diiuser is rotary with the compressor to effect the energy conversion without unduly increasing the radius of the rotating structure.

Another object of the invention is a diffuser in accordance with the two initial objects in which thediifuser includes a portion rotational with the compressor, a portion freely rotatable as a follower, and a stationary portion in which the nal conversion is effected.

Other objects and features of the invention will be readily apparent to those skilled in the art from the specification and appended drawing illustrating certain preferred embodiments in which:

Figure 1 is a side elevational view of a compressor embodyinga diffuser according to the present invention.

Figure 2 is a View partly in section and partly in elevation of the diffuser and compressor.

Figure 3 is an enlarged partial view similar to Figure 2.

Figure 4 is a sectional view on the line IV--IV of Figure 2.

Figure 5 is a view similar to Figure 2 showing a modied form of diffuser.

Figure 6 is a view similar to Figure 2 showing' another form of diffuser.

Figure 7 is a view similar to Figure 2 showing another form of diffuser.

Figure 8 is a view similar to Figure 2 showing still another form of diffuser.

In the form of the invention illustrated in the Figures 1 through 4 there is provided a divided casing I in which is rotatably mounted a rotor on bearings 3 and 4. Rigidly mounted on the shaft 2 is a rotor indicated generally at 5 which comprises side walls 6 and 1 connected by a plurality of radially extending ns 8. Integral with the side wall 6 is an air or gas inlet at 9 at the axis of the machine. The diffuser of this form of the invention comprises three portions, one rotatable with the rotor 5, a freely rotatable i91- lower portion and a stationary portion. Integral with the fins 8 of the rotor is an annular rib II carrying an annular ring i2 forming a part of the rotary portion of the diffuser. The side walls of the ring l2 and the inwardly directed ends of the rotor walls 6 and l form the rotatable diffuser passages I3. The following portion of the diffuser is comprised by side walls I4 and I5 joined together and to a center portion I6 by a plurality of spaced pins Il. The surfaces at the sides of the central portion I6 and the inwardly directed portions of the walls I4 and I5 form the walls of the diffuser passage in the follower portion. This follower portion is freely rotatable upon the bearings I8 and I9. The stationary portion of the diffuser is formed by the walls 2l and 22 of the casing I and by the annular ring 23 joined to the casing sections by the spaced pins 24. The periphery of the casing I forms a collector spacer 25 into which the air or gas from the diffuser passages is delivered.

While the gures of the drawing illustrate a pair of diuser passages through which air or other fluid is discharged from the rotary compressor, the invention contemplates a greater number of these passages being provided to further reduce the radial length of the diffuser.

In the use of annular diffuser for the converlsion of the rotational energy of a fluid to pressure energy, with the use of divergent walls a decrease in the velocity of the fluid is secured not only by its moving to a portion of greater radius but also by the increased width of the diffuser passage. This increase in width can only be effected at a denite maximum divergent angle which, if exceeded, will defeat the object of the diffuser which is to slow the velocity of the air by increasing the area of its path to convert its rotational energy to pressure energy. To effect this increase in flow area eciently the gas must remain in contact With the walls of the diffuser passage. if the angle of divergence of the passage is too great, the fluid flow separates from the wall and the fluid column fails to increase its Width. Accordingly, for the maximum conversion of rotational into pressure energy, diffusers having a considerable radial length have been provided which greatly increases the overall size and weight of the compressor or pump.

According to the present invention the single diffuser passage is divided into a plurality of parallel diuser passages having the same divergent angle and thus providing for the same total change in passage width from the inlet to the outlet over a much smaller radial length. Thus, with the use of three divergent passages for a given rotary collector, a given change in diffuser passagewidth from entrance to exit will be eiected in one third of the radial diifuser length over the length required for a single passage. While the change in passage Width is effected in this reduced radial length, the overall length of the diifuser can not be quite so reduced for the same conversion of energy because the gas ilow increases in area, not only because of the increased width of the diffuser passage, but also because it is moving to a portion of greater radius. However, a considerable saving in the overall radius of the machine and of its weight is effected by dividing the diiuser passage into a plurality of parallel passages of the same permissable divergence.

In the form of the invention illustrated in Figures 1 through 4, thefdiifuser passages are in three sections, the rst section', where the fluid has the greatest rotational velocity, being rotated with the rotary compressor, the second and intermediate section, where the iluid has a lowered rotational velocity, being freely rotatable to follow the rotation of the compressor by iluid drag and the third section, where the fluid has the lowest rotational velocity being provided in the 'stationary casing.

In the form of the invention illustrated in Figure 5 the follower diiuser section has been omitted and the diffuser passages are formed in two sections, one rotating with the compressor rotor and indicated at 26 and the other stationary in the casing and indicated at 2l. The overall lengths of the diluser passages remain the same but their length in the stationary and compressor rotor sections have been increased.

In the form of the invention illustrated in Figure 6, the diffuser passages are formed in single sections indicated at 28 and rotatable with the compressor rotor, again the overall length of the diiuser passages remaining the same.

In the form of the invention illustrated in Figure 7 the diiuser passages are formed in single stationary sections indicated at 23 and disposed in the casing i.

In the form of the invention illustrated at Figure 8 there is shown a construction having certain limitations but providing a light and simple construction for the compressor rotor with integral diiuser passages. Here the fins 8 of the rotor are disposed between side walls 3l and 32 of sheet metal which are bent outwardly beyond the peripheral ends of the ns as at 33 and 34. Supported on the ns 8 are a pair oi sheet metal walls 35 and 36 bent outwardly beyond the ends of the fins in divergent relation but to a lesser extent than the portions 33 and 34 of the side walls 3| and 32. The spaces between the side walls portion 33 and the divergent portion of wall 35, between the divergent portions of walls 35 and 36, and between the divergent portion of wall 36 and the side wall 34 form three parallel divergent diffuser passages, in accordance with ther present invention, which are rotatable with the compressor rotor.

It will be seen that the diiusers, according to the present invention, are usable with any type of rotary compressor or pump and upon any fluid, gas or liquid, in which rotational energy of the iluid is to be transformed into pressure energy. The term compressor used in the claims is to be construed to include fluid pumps.

While certain preferred embodiments of the 4 invention have been specifically disclosed. it is understood that the invention is not limited thereto. as many variations will be readily apparent to those skilled in the art and the inven- 5 tion is to be given its broadest possible interpretation within the terms of the following claims What is claimed is:

1. In a rotary compressor, a diffuser in which the rotational energy of a fluid delivered from the compressor rotor is converted into pressure energy. said diuser being composed of a plurality of substantially parallel annular passages increasing in width from the inlet toward the outlet of the diffuser, said diffuser passages being formed of three sections, with the interior section rotating with the speed of rotation of the compressor rotor, an intermediate section rotating at a reduced speed and with the outer section stationary.

2. In a rotary compressor, a diiuser in which the rotational energy of a duid delivered from the compressor rotor is converted into pressure energy, said diiuser being composed of a plurality of substantially parallel, annular passages having walls diverging from the inlet toward the outlet, said diiuser passages being formed of three sections with the interior section rotatable with the compressor rotor, an intermediate section freely rotatable as a follower by fluid drag from the rotation of the rotor, and with the outer section stationary.

3. In a rotary compressor, a diffuser in which the rotation of a fluid delivered from the compressor rotor is converted into pressure energy, said diiuser being composed of a plurality of substantially parallel, annular passages having vwalls diverging from the inlet toward the outlet, said diiuser passages being formed in at least two sections with the interior section rotatable with the compressor rotor and the outer section stationary.

4. In a rotary compressor, a ditfuser in which the rotation of a iluid delivered from the compresser rotor is converted into pressure energy,

said diffuser being composed of a plurality of substantially parallel, annular passages having walls diverging from the inlet toward the outlet, the walls of said diiuser passages being ro- 60 tatable with the compressor rotor.

5. In a rotary compressor, a diiuser in which the rotational energy of a fluid delivered from the compressor rotor is converted into pressure energy, said diffuser comprising opposed unbroken walls dening between them a space divergent, in a cross section taken through the rotor axis, from the inlet to the outlet, said diffuser passage being formed in two portioins, an inner portion formed by opposed walls rotatable with the rotor, the outer portiton being formed by opposed stationary walls, the wall curvature between the two portions being continuous.

PAUL KOLISMAN.

REFERENCES CITED UNITED STATES PATENTS Number Name Date 1,091,581 Ljungstrom Mar. 31, 1914 1,889,816 White Dec. 6, 1932 2,114,285 Berger Apr. 19, 1938 2,334,625 Heppner Nov. 16, 1943 

